A foreign cyberattack may have caused the official voter registration website for the EU referendum to crash hours before the final deadline, according to a report by MPs.

The Commons Public Administration and Constitutional Affairs Committee (PACAC) says the crash had indications of being a distributed denial of service attack - overwhelming the site and thwarting people's attempts to sign up.

Following the website's failure on 7 June 2016, the Government had to rush through emergency regulations to extend the deadline.

Although the Commons committee did not identify who may have been responsible, the MPs noted that Russia and China have used an approach to cyberattacks "based on an understanding of mass psychology and of how to exploit individuals".

PACAC said it was "deeply concerned" about the allegations of foreign interference.

Video:Feb - Govt must 'up its game' to repel cyber attacks

The group's Conservative chairman, Bernard Jenkin, warned the possibility could not be ruled out because of how other countries have suffered cyberattacks during their elections - with the US currently investigating claims that Russia sought to meddle in the outcome of last November's presidential race.

Despite its findings, a Cabinet Office spokeswoman dismissed the theory - and said the outage was owing to a spike in demand in the hours before the registration deadline.

She added: "There is no evidence to suggest malign intervention. We conducted a full review into the outage and have applied the lessons learned."

PACAC has urged authorities to keep a close eye on cyber activity during elections and referendums in future as a "precautionary" measure, and stand ready to respond to cyberattacks should they occur.

However, it said last year's incident had no material effect on the outcome of the referendum.

Image:David Cameron's resignation was also criticised in the 87-page report

Elsewhere in the committee's 87-page report, David Cameron was criticised for his decision to resign as prime minister after his administration lost the EU referendum.

It said leaders who call referendums in future should be prepared to remain in office and implement the result - irrespective of the outcome.